A known cardiac catheter is disclosed in Amrine, U.S. Pat. No. 4,129,129. This catheter includes two sets of openings, namely those at the rounded nose portion of the catheter which is intended to enter the inferior vena cava, and those at the juncture between the differing diameter portions of this catheter, which are intended to be placed in the right atrium. The use of such a catheter, however, has been relatively troublesome for several reasons, including the fact that a part of the catheter must be removed in order to achieve the desired flow through the different openings. Furthermore, this overall design is somewhat difficult to use because it is relatively large and because it is also essentially stiff.
Various other medical suction devices are also known, such as that shown in U.S. Pat. No. 3,395,705 to Hamilton, which includes flow regulating means for use in a suction line between a medical catheter and a suction pump for the purpose of varying the amounts of suction being applied to a catheter. Similar types of suction devices are also shown in Swedish Patent Publication No. 337,888; Swedish Patent Publication No. 429,005; Swedish Patent Application No. 84.00747-5; and U.S. Pat. No. 3,834,388 to Sauer. In addition, a heart catheter intended to be used in an entirely different manner from those of the present invention and also as compared to the above-noted Amrine patent are shown in U.S. Pat. No. 2,935,068 to Donaldson.